Abstract

We are developing optical techniques to generate and receive ultrasound for various biomedical applications including high frequency 2D arrays, molecular imaging, and microfluidic devices. A 2D synthetic receive array uses a HeNe laser to probe the surface displacements of a thin reflective membrane. Images with near optimal resolution and wide fields of view have been produced at 10 to 50 MHz. A 75 MHz transmitting 2D array element relies on the thermoelastic effect. A 10 ns laser pulse is focused onto a 25 μm thick black polydimethylsiloxane(PDMS) film spin coated on a pure PDMS substrate. Our work in optoacoustic molecular imaging combines ultrafast lasers with high frequency ultrasound. When ultrafast laser pulses are focused into transparent media, laser induced optical breakdown (LIOB) produces acoustic emission and cavitation bubbles. A real‐time acoustic technique has been developed to characterize LIOB in dendrimer nanocomposite (DNC) solutions. Lamb waves propagating in thin membranes have found widespread use in microfluidic devices. We use the thermoelastic effect as a noncontact method to generate continuous‐wave Lamb waves in gold‐coated membranes. We believe these results demonstrate the potential of optoacoustic methods for a broad range of applications in biomedical ultrasonics.